Dan Potter, Professor
Department of Entomology
University of Kentucky College of Agriculture

Large tent caterpillars are leaving
infested trees in search of pupation sites. This may result in the need for
an insecticide application to protect pregnant mares.

Field tests conducted by UK entomologists
as part of a Grayson-Jockey Club-funded research project indicate that dry residues
of a 0.5% tank mix of Astro insecticide will quickly kill large tent caterpillars
crawling over or through treated pasture grass. This is a rate of 1.6 fl. oz.
of product per gallon of water. Six-foot wide barriers have been used in field
tests but narrower bands may be adequate.

"Perimeter Treatment" as
described on the label includes "lawn areas adjacent or around private
homes, duplexes, ....garages, fence lines, storage sheds, barns, soil, trunks
of woody ornamentals and other areas where pests congregate or have been seen".

Farms needing to stop tent caterpillars
from crawling into pastures from adjacent untreated areas may want to consider
this tactic. Alternatively, Astro can be applied to lower tree trunks or to
the ground around the base of trees. Applications should be made outside of
the perimeter so that the caterpillars will be killed before entering the pasture.